PodOne Posted December 18, 2021 Report Share Posted December 18, 2021 Evening all Been of the metric generation the imperial size are a bit of a mystery to me! I have the bigger TRGB brass outlet which I believe is 1/2" UNF 20 TPI? which screws into the tank outlet. What I'm wanting to do is fit a Sytec fuel isolator tap which has 1/4" BSP outlets. Interestingly the TRGB outlet will screw into the tap at either end. Confused I am! Which straight fitting do I need to order from where to get from the tank outlet to the tap? I'll use the TRGB fitting on the end of the tap to the pre filter. I know its being done as I've seen pictures somewhere. Any help appreciated. Thanks Andy PS One last thing Rimmers strikes again the sender plate holes under sized to bolt the sender to the tank needed to be enlarged Quote Link to post Share on other sites
RobH Posted December 18, 2021 Report Share Posted December 18, 2021 Unfortunately this is a can of worms Andy. 1/4 BSP (parallel) is 1/2 inch OD x 19tpi. (BSP is sized by the bore of old imperial pipes, not the thread diameter, which is why the numbers are confusing) The TRGB adaptor may fit the tap for a few threads but should bind when part way in because of the pitch error. If you use it that way it may leak. Also BSP comes in taper or parallel thread forms so you need to know which one it is to get the correct mating part. I suspect the Sytec tap may be taper as that is what they seem to supply as adaptors, although yours may be different of course: https://www.fuelpumpsonline.co.uk/fuel-taps-5142-c.asp Quote Link to post Share on other sites
PodOne Posted December 18, 2021 Author Report Share Posted December 18, 2021 (edited) Thanks Rob You're not kidding a real can of worms!! By luck or coincidence it looks like I have the exact tap in the link. Here's a few pic's of how far I've got the tap threads are parallel and the TRGB outlet will thread into it and the tank so I suppose I could just buy another TRGB fitting and rubber pipe between the two and make a bracket for the tap. Was hoping to have a rigid connection from tank to tap and no rubber pipe. So perhaps a straight male parallel 1/4 BSP both ends required?? Andy Edited December 18, 2021 by PodOne Quote Link to post Share on other sites
Drewmotty Posted December 18, 2021 Report Share Posted December 18, 2021 57 minutes ago, RobH said: Also BSP comes in taper or parallel thread forms so you need to know which one it is to get the correct mating part. Both BSP Taper threads and BSP Parallel male threads mate with BSP Parallel female threads. Adaptors are best sourced from your local hydraulic equipment supplier. Most fittings will be rated for very high pressures compared with automotive applications and so the bores can be usefully bored out to increase the flow rate and reduce pressure drops. Quote Link to post Share on other sites
Drewmotty Posted December 18, 2021 Report Share Posted December 18, 2021 (edited) You can use a straight male/male adaptor in the tank and a male/female swivel in the valve. The female swivel will screw directly to the tank adaptor and allow you to swivel the valve to a convenient angle. No intermediate pipe will be required. Make sure that the ball valve is a full flow type with the full diameter right through when open. As above you can drill out high pressure fittings to ensure maximum flow and avoid cavitating the pump. Edited December 18, 2021 by Drewmotty Quote Link to post Share on other sites
PodOne Posted December 18, 2021 Author Report Share Posted December 18, 2021 4 minutes ago, Drewmotty said: You can use a straight male/male adaptor in the tank and a male/female swivel in the valve. The female swivel will screw directly to the tank adaptor and allow you to swivel the valve to a convenient angle. No intermediate pipe will be required. Make sure that the ball valve is a full flow type with the full diameter right through when open. As above you can drill out high pressure fittings to ensure maximum flow and avoid cavitating the pump. Sounds like a plan thanks. I'll take the fuel tap and tank outlet into Pirtek and source the fittings. The tap is a full flow same diameter as the tank outlet and will drill out the adaptors if required. Thanks Drew? and Rob. Andy Quote Link to post Share on other sites
Mike C Posted December 19, 2021 Report Share Posted December 19, 2021 It you're planning to install the tap near the tank outlet make sure that you can get to it with the boot lining in place. The reason I installed a ball valve was to prevent gross fuel spillage in the event of a ruptured pipeline or component as well as to make it easier to change fuel filters , for these purposes I need ready access. Quote Link to post Share on other sites
Schnippel Posted December 19, 2021 Report Share Posted December 19, 2021 Hi there , Always install suction lines in bends. Narrow angles of 90 degrees promote cavitation and prevent free flow to the pump. That is a Bosch recommendation. Regards Ralf Quote Link to post Share on other sites
PodOne Posted December 19, 2021 Author Report Share Posted December 19, 2021 1 hour ago, Schnippel said: Hi there , Always install suction lines in bends. Narrow angles of 90 degrees promote cavitation and prevent free flow to the pump. That is a Bosch recommendation. Regards Ralf Thanks Ralf if all goes to plan following the above advice the 90 degree will be deleted. Andy Quote Link to post Share on other sites
PodOne Posted December 23, 2021 Author Report Share Posted December 23, 2021 Hi all I'm still stuck finding a male/male adaptor to get from the tank to a swivel female/male to the tap. I would seem need a male/male with the same threads as the TRGB big bore outlet as in the picture above which is I think 1/2" UNF 20 TPI?? What ever it is the TRGB outlet will screw into the 1/4" BSP tap as well as the tank. Then a swivel female (1/2" UNF 20TPI? /male (1/4" BSP) to fit the on the end of male/male adaptor would be helpful then to get the tap in the right position. I still can't get my head around why the 1/4 BSP male/male adaptor will screw into the tap the same as the TRGB outlet but it won't screw into the tank yet the TRGB will!! Sorry to be a pain but can anyone direct me to where I can get the correct fitting to do the job? Thanks Andy Quote Link to post Share on other sites
RobH Posted December 23, 2021 Report Share Posted December 23, 2021 This is 1/2 unf to 1/4 bsp: https://www.merlinmotorsport.co.uk/p/adaptor-1-2unf-x-1-4bsp-male-male-m-8unf-4bsp The only sort of 1/2 unf-1/2 unf I can find is this. Although not intended for fuel use it is alloy so OK for the tank as it won't be under pressure. https://www.ebay.co.uk/itm/351072002260?hash=item51bd85a0d4:g:gY4AAOSwNnRYlZwB Quote Link to post Share on other sites
PodOne Posted December 23, 2021 Author Report Share Posted December 23, 2021 40 minutes ago, RobH said: This is 1/2 unf to 1/4 bsp: https://www.merlinmotorsport.co.uk/p/adaptor-1-2unf-x-1-4bsp-male-male-m-8unf-4bsp The only sort of 1/2 unf-1/2 unf I can find is this. Although not intended for fuel use it is alloy so OK for the tank as it won't be under pressure. https://www.ebay.co.uk/itm/351072002260?hash=item51bd85a0d4:g:gY4AAOSwNnRYlZwB Thanks Rob much appreciated . Andy Quote Link to post Share on other sites
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